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Date: Thu, 10 Aug 2017 16:28:02 -0700
From: Wanpeng Li <kernellwp@...il.com>
To: linux-kernel@...r.kernel.org, kvm@...r.kernel.org
Cc: Paolo Bonzini <pbonzini@...hat.com>,
Radim Krčmář <rkrcmar@...hat.com>,
Wanpeng Li <wanpeng.li@...mail.com>
Subject: [PATCH] KVM: MMU: Bail out immediately if there is no available mmu page
From: Wanpeng Li <wanpeng.li@...mail.com>
Bailing out immediately if there is no available mmu page to alloc.
Cc: Paolo Bonzini <pbonzini@...hat.com>
Cc: Radim Krčmář <rkrcmar@...hat.com>
Signed-off-by: Wanpeng Li <wanpeng.li@...mail.com>
---
arch/x86/kvm/mmu.c | 36 +++++++++++++++++++++++++++---------
arch/x86/kvm/paging_tmpl.h | 3 ++-
2 files changed, 29 insertions(+), 10 deletions(-)
diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
index 849312d..e7d1bb1 100644
--- a/arch/x86/kvm/mmu.c
+++ b/arch/x86/kvm/mmu.c
@@ -3257,7 +3257,7 @@ static bool fast_page_fault(struct kvm_vcpu *vcpu, gva_t gva, int level,
static bool try_async_pf(struct kvm_vcpu *vcpu, bool prefault, gfn_t gfn,
gva_t gva, kvm_pfn_t *pfn, bool write, bool *writable);
-static void make_mmu_pages_available(struct kvm_vcpu *vcpu);
+static int make_mmu_pages_available(struct kvm_vcpu *vcpu);
static int nonpaging_map(struct kvm_vcpu *vcpu, gva_t v, u32 error_code,
gfn_t gfn, bool prefault)
@@ -3297,7 +3297,8 @@ static int nonpaging_map(struct kvm_vcpu *vcpu, gva_t v, u32 error_code,
spin_lock(&vcpu->kvm->mmu_lock);
if (mmu_notifier_retry(vcpu->kvm, mmu_seq))
goto out_unlock;
- make_mmu_pages_available(vcpu);
+ if (make_mmu_pages_available(vcpu) < 0)
+ goto out_unlock;
if (likely(!force_pt_level))
transparent_hugepage_adjust(vcpu, &gfn, &pfn, &level);
r = __direct_map(vcpu, write, map_writable, level, gfn, pfn, prefault);
@@ -3376,7 +3377,10 @@ static int mmu_alloc_direct_roots(struct kvm_vcpu *vcpu)
if (vcpu->arch.mmu.shadow_root_level == PT64_ROOT_LEVEL) {
spin_lock(&vcpu->kvm->mmu_lock);
- make_mmu_pages_available(vcpu);
+ if(make_mmu_pages_available(vcpu) < 0) {
+ spin_unlock(&vcpu->kvm->mmu_lock);
+ return 1;
+ }
sp = kvm_mmu_get_page(vcpu, 0, 0, PT64_ROOT_LEVEL, 1, ACC_ALL);
++sp->root_count;
spin_unlock(&vcpu->kvm->mmu_lock);
@@ -3387,7 +3391,10 @@ static int mmu_alloc_direct_roots(struct kvm_vcpu *vcpu)
MMU_WARN_ON(VALID_PAGE(root));
spin_lock(&vcpu->kvm->mmu_lock);
- make_mmu_pages_available(vcpu);
+ if (make_mmu_pages_available(vcpu) < 0) {
+ spin_unlock(&vcpu->kvm->mmu_lock);
+ return 1;
+ }
sp = kvm_mmu_get_page(vcpu, i << (30 - PAGE_SHIFT),
i << 30, PT32_ROOT_LEVEL, 1, ACC_ALL);
root = __pa(sp->spt);
@@ -3424,7 +3431,10 @@ static int mmu_alloc_shadow_roots(struct kvm_vcpu *vcpu)
MMU_WARN_ON(VALID_PAGE(root));
spin_lock(&vcpu->kvm->mmu_lock);
- make_mmu_pages_available(vcpu);
+ if (make_mmu_pages_available(vcpu) < 0) {
+ spin_unlock(&vcpu->kvm->mmu_lock);
+ return 1;
+ }
sp = kvm_mmu_get_page(vcpu, root_gfn, 0, PT64_ROOT_LEVEL,
0, ACC_ALL);
root = __pa(sp->spt);
@@ -3458,7 +3468,10 @@ static int mmu_alloc_shadow_roots(struct kvm_vcpu *vcpu)
return 1;
}
spin_lock(&vcpu->kvm->mmu_lock);
- make_mmu_pages_available(vcpu);
+ if (make_mmu_pages_available(vcpu) < 0) {
+ spin_unlock(&vcpu->kvm->mmu_lock);
+ return 1;
+ }
sp = kvm_mmu_get_page(vcpu, root_gfn, i << 30, PT32_ROOT_LEVEL,
0, ACC_ALL);
root = __pa(sp->spt);
@@ -3869,7 +3882,8 @@ static int tdp_page_fault(struct kvm_vcpu *vcpu, gva_t gpa, u32 error_code,
spin_lock(&vcpu->kvm->mmu_lock);
if (mmu_notifier_retry(vcpu->kvm, mmu_seq))
goto out_unlock;
- make_mmu_pages_available(vcpu);
+ if (make_mmu_pages_available(vcpu) < 0)
+ goto out_unlock;
if (likely(!force_pt_level))
transparent_hugepage_adjust(vcpu, &gfn, &pfn, &level);
r = __direct_map(vcpu, write, map_writable, level, gfn, pfn, prefault);
@@ -4788,12 +4802,12 @@ int kvm_mmu_unprotect_page_virt(struct kvm_vcpu *vcpu, gva_t gva)
}
EXPORT_SYMBOL_GPL(kvm_mmu_unprotect_page_virt);
-static void make_mmu_pages_available(struct kvm_vcpu *vcpu)
+static int make_mmu_pages_available(struct kvm_vcpu *vcpu)
{
LIST_HEAD(invalid_list);
if (likely(kvm_mmu_available_pages(vcpu->kvm) >= KVM_MIN_FREE_MMU_PAGES))
- return;
+ return 0;
while (kvm_mmu_available_pages(vcpu->kvm) < KVM_REFILL_PAGES) {
if (!prepare_zap_oldest_mmu_page(vcpu->kvm, &invalid_list))
@@ -4802,6 +4816,10 @@ static void make_mmu_pages_available(struct kvm_vcpu *vcpu)
++vcpu->kvm->stat.mmu_recycled;
}
kvm_mmu_commit_zap_page(vcpu->kvm, &invalid_list);
+
+ if (!kvm_mmu_available_pages(vcpu->kvm))
+ return -ENOSPC;
+ return 0;
}
int kvm_mmu_page_fault(struct kvm_vcpu *vcpu, gva_t cr2, u64 error_code,
diff --git a/arch/x86/kvm/paging_tmpl.h b/arch/x86/kvm/paging_tmpl.h
index b0454c7..3bb90ce 100644
--- a/arch/x86/kvm/paging_tmpl.h
+++ b/arch/x86/kvm/paging_tmpl.h
@@ -819,7 +819,8 @@ static int FNAME(page_fault)(struct kvm_vcpu *vcpu, gva_t addr, u32 error_code,
goto out_unlock;
kvm_mmu_audit(vcpu, AUDIT_PRE_PAGE_FAULT);
- make_mmu_pages_available(vcpu);
+ if (make_mmu_pages_available(vcpu) < 0)
+ goto out_unlock;
if (!force_pt_level)
transparent_hugepage_adjust(vcpu, &walker.gfn, &pfn, &level);
r = FNAME(fetch)(vcpu, addr, &walker, write_fault,
--
2.7.4
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